Some copper (ll) sulphate pentahydrate (CuSO4 5H2O), was heated at 120 oC with the following results. Wt of crucible = 10.00 g; Wt of crucible + CuSO4 5H2O =14.98g; Wt of crucible + residue = 13.54 g. How many molecules of water of crystalization were lost?
[H = 1, Cu = 63.5, O = 16, S = 32]
[H = 1, Cu = 63.5, O = 16, S = 32]
-
A.
1 -
B.
2 -
C.
3 -
D.
4 -
E.
5
Correct Answer: Option D
Explanation
CuSO4 + 5H 2O
Wt CuSO4 + 5H2O = 14.98 – 10.00
= 4.98 gm
Wt of residue or CuSO4 = 13.54 – 10.00 =3.54
Wt of water lost = 4.98 – 3.54 = 1.44
Molecules of H2O lost = 5 – 1 = 4